In recent years, photographic materials are sought having various capabilities, improvement of sensitivity, storability and printing durability.
On the other hand, the need for simple and rapid development processing is also recently increasing, and low replenishment of the processing solution is a need of high priority. To cope with these requirements, use of a silver halide grain having a high solubility and a high silver chloride content is advantageous. For reducing the wastes, the image density is preferably increased with a small amount of silver. And, as well known in the art, a tabular grain is suitable for this in view of sensitivity, granularity, sharpness and color sensitization efficiency.
With respect to the tabular grain having a high silver chloride content, examples of the tabular grain having a {111} face on the major faces are described, for example, in JP-B-64-8326 (the term "JP-B" as used herein means an "examined Japanese patent publication"), JP-B-64-8325, JP-B-64-8324, JP-A-1-250943 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-B-3-14328, JP-B-4-81782, JP-B-5-40298, JP-B-5-39459, JP-B-5-12696, JP-A-63-213836, JP-A-63-218938, JP-A-63-281149 and JP-A-62-218959.
However, when a large amount of sensitizing dyes are adsorbed to AgX grains, a grain having a {100} face usually exhibits better color sensitization property. Accordingly, development of the tabular grain having {100} faces as major faces is demanded. The {100} tabular grain having major faces in the right angled parallelogram shape is described in JP-A-51-88017, JP-B-64-8323, European Patent 0,534,395A1, U.S. Pat. Nos. 5,292,632, 5,264,337 and 5,320,938, JP-A-5-313273, JP-A-6-59360 and WO94/22051.
In order to increase the solubility and improve the processability, use of a silver halide grain having a high silver chloride content is advantageous, however, the silver chloride has an intrinsic wavelength region shorter in the wavelength than silver bromide and therefore, absorption of blue light and ultraviolet light is small and the grain is liable to be low sensitive. In the case of using the grain in a photographic light-sensitive material for medical X ray, needless to say about an UV emission screen and a regular system phosphor screen, a so-called ortho-system phosphor screen emits light in the blue and ultraviolet regions and therefore, the emulsion is naturally limited in the silver chloride content. Further, in the case of using the grain in a color light-sensitive material, the emulsion for use in a blue-sensitive layer is naturally limited in the silver chloride content.
In order to improve the processability without causing any reduction in the sensitivity to blue light, a mixed crystal of silver chloride and silver bromide is effective, however, formation of the mixed crystal is liable to invite broadening of the halogen composition distribution among silver halide grains and when the emulsion is dissolved, the aging stability may be worsened or softening may be caused.
The above-described publications of conventional technique describe a {100} tabular grain having a Br content in the vicinity of 50 mol %, however, they are quite unsatisfactory with respect to the {100} tabular grain having a narrow halogen composition distribution among grains and a Br content in the vicinity of 50 mol %.